The proposed work consists of the following four projects: I. Quantitative Characterization of the In Vitro Neoplastic Transformation of Syrian Hamster Embryo Cells (SHE cells, 13-days gestation) - The Development of Carcinogenic Bioassay. II. Somatic Genetics on the Progression in Neoplastic Transformation: Studies of the Spontaneous Initiation and Progression Toward Neoplastic Transformation of Syrian Hamster Cells. III. Changes in Gene Expression Accompanying Neoplastic Transformation. IV. Transformation of Syrian hamster Embryo Cells by HSV-2 DNA.